Let's turn now to an example of a prime and analyze the routes through it. Here is an intended function:

[ if a is zero -> x := 0 else if b is positive -> x := y + 1 else -> x := y - 1 ]

The possible paths through this prime are governed by two conditions, which we will call C1 and C2.

C1:

`a`

is zero.C2:

`b`

is positive.

There are three paths through the code, because if C1 is true, we don't care whether C2 is true or not. So our truth table has three cases.

C1 | C2 | Case |
---|---|---|

T | X | C1 |

F | F | C1′ ∧ C2′ |

F | T | C1′ ∧ C2 |